In article , John
Szalay wrote:

In August, while cataloging the debris field around the wreck of a Japanese
midget submarine, HURL submarine pilot Terry Kerby ran across the inverted
keel of a "flying boat"
A Martin JRM-1 Mars named "Marshall Mars"


In the spring of 1950, during a test flight off of Diamond Head, one of
"Marshall Mars" engines caught fire, and the pilot landed in the open
ocean. Although the crew got out safely and a fireboat was soon on the
scene, the plane burned, exploded and sank. The cause was thought to be a
leaking fuel line, although it could not be confirmed because the wreckage
vanished, swallowed by the ocean.


http://starbulletin.com/2004/12/14/news/story4.html

two of the Mars flying boats are still around.
http://www.martinmars.com/

Thanks John, interesting.